Catalysts for conversion of olefins

ABSTRACT

A composition active for the conversion of olefins comprising magnesium oxide and an olefin disproportionation catalyst in admixture.

This application is a division of application Ser. No. 205,350, filedDec. 6, 1971, now U.S. Pat. No. 3,865,751 which in turn was a divisionof application Ser. No. 6,045, filed Jan. 26, 1970, now U.S. Pat. No.3,660,506, which in turn was a continuation of application Ser. No.678,499, filed Oct. 27, 1967, now abandoned, which in turn was acontinuation-in-part of application Ser. No. 627,668, filed Apr. 3,1967, now abandoned.

This invention relates to the conversion of olefin hydrocarbons by theolefin reaction.

The olefin reaction is defined as a process for the catalytic conversionover a catalyst of a feed comprising one or more ethylenicallyunsaturated compounds to produce a resulting product which contains atleast ten percent by weight of product compounds, which productcompounds can be visualized as resulting from at least one primaryreaction, as defined below, or the combination of at least one primaryreaction and at least one unsaturated bond isomerization reaction, andwherein the sum of the compounds contained in said resulting productconsisting of hydrogen, saturated hydrocarbons, and compounds which canbe visualized as formed by skeletal isomerization but which cannot bevisualized as formed by one or more of the above-noted reactions,comprises less than 25 percent by weight of the total of said resultingproduct. Feed components and unsaturated bond isomers thereof are notincluded in the resulting product for the purpose of determining theabove-noted percentages.

In the olefin reaction, as defined above, the primary reaction is areaction which can be visualized as comprising the breaking of twoexisting unsaturated bonds between first and second carbon atoms andbetween third and fourth carbon atoms, respectively, and the formationof two new unsaturated bonds between said first and third and betweensaid second and fourth carbon atoms. Said first and second carbon atomsand said third and fourth carbon atoms can be in the same or differentmolecules.

The olefin reaction according to this invention is illustrated by thefollowing reactions:

1. The disproportionation of an acyclic mono- or polyene having at leastthree carbon atoms into other acyclic mono- or polyenes of both higherand lower number of carbon atoms; for example, the disproportionation ofpropylene yields ethylene and butenes; the disproportionation of1,5-hexadiene yields ethylene and 1,5,9-decatriene;

2. The conversion of an acyclic mono- or polyene having three or morecarbon atoms and a different acyclic mono- or polyene having three ormore carbon atoms to produce different acyclic olefins; for example, theconversion of propylene and isobutylene yields ethylene and isopentene;

3. The conversion of ethylene and an internal acyclic mono- or polyenehaving four or more carbon atoms to produce other olefins having a lowernumber of carbon atoms than that of the acyclic mono- or polyenes; forexample, the conversion of ethylene and 4-methylpentene-2yields3-methylbutene-1 and propylene;

4. The conversion of ethylene or an acyclic mono- or polyene havingthree or more carbon atoms and a cyclic mono- or cyclic polyene toproduce an acyclic polyene having a higher number of carbon atoms thanthat of any of the starting materials; for example, the conversion ofcyclohexene and 2-butene yields 2,8-decadiene; the conversion of1,5-cyclooctadiene and ethylene yields 1,5,9-decatriene;

5. The conversion of one or more cyclic mono- or cyclic polyenes toproduce a cyclic polyene having a higher number of carbon atoms than anyof the starting materials; for example, the conversion of cyclopenteneyields 1,6-cyclodecadiene and continued reaction can produce highermolecular weight material;

6. The conversion of an acyclic polyene having at least seven carbonatoms and having at least five carbon atoms between any two double bondsto produce acyclic and cyclic mono- and polyenes having a lower numberof carbon atoms than that of the feed; for example, the conversion of1,7-octadiene yields cyclohexene and ethylene; or

7. The conversion of one or more acyclic polyenes having at least threecarbon atoms between any two double bonds to produce acyclic and cyclicmono- and polyenes generally having both a higher and lower number ofcarbon atoms than that of the feed material; for example, the conversionof 1,4-pentadiene yields 1,4-cyclohexadiene and ethylene.

By disproportionation as used herein is meant the conversion ofhydrocarbons into similar hydrocarbons of both higher and lower numbersof carbon atoms.

An object of this invention is to convert olefins by the olefinreaction.

Another object of this invention is to disproportionate olefins atrelatively high conversion rates.

Other aspects, objects and the advantages of our invention are apparentin the written description and the claims.

According to this invention, an olefin capable of undergoing the olefinreaction is converted by contacting with a combined catalyst comprisingan olefin reaction catalyst and a double bond isomerization catalystunder suitable conditions for obtaining olefin reaction. Furtheraccording to the invention an olefin capable of undergoing the olefinreaction is converted by contacting with a mixed bed of adisproportionation catalyst and magnesium oxide. Further according tothe invention an olefin capable of undergoing the olefin reaction isconverted by contacting with a disproportionation catalyst treated witha metallic alkali metal.

Olefins applicable for use in the process of the invention includeacyclic mono- and polyenes having at least 3 carbon atoms per moleculeand cycloalkyl and aryl derivatives thereof; cyclic mono- and polyeneshaving at least four carbon atoms per molecule and alkyl and arylderivatives thereof; mixtures of two or more of the above olefins; andmixtures of ethylene with one or more of the above olefins. Many usefulreactions are accomplished with such acyclic olefins having 3-30 carbonatoms per molecule and with such cyclic olefins having 4-30 carbon atomsper molecule.

Some specific examples of acyclic olefins suitable for reactions of thisinvention include propylene, 1-butene, isobutene, 2-butene,1,3-butadiene, 1-pentene, 2-pentene, isoprene, 1-hexene, 1,4-hexadiene,2-heptene, 1-octene, 2,5-octadiene, 2,4,6-octatriene, 2-nonene,1-dodecene, 2-tetradecene, 1-hexadecene, 5,6-dimethyl-2,4-octadiene,2-methyl-1-butene, 2-methyl-2-butene, 1,3-dodecadiene,1,3,6-dodecatriene, 3-methyl-1-butene, 1-phenylbutene-2,7,7-diethyl-1,3,5-decatriene, 1,3,5,7,9-octadecapentaene,1,3-eicosadiene, 4-octene, 3-eicosene and 3-heptene, and the like, andmixtures thereof.

Some specific examples of cyclic olefins suitable for the reactions ofthis invention are cyclobutene, cyclopentene, cyclohexene,3-methylcyclopentene, 4-ethylcyclohexene, 4-benzylcyclohexene,cyclooctene, 5-n-propylcyclooctene, cyclodecene, cyclododecene,3,3,5,5-tetramethylcyclononene, 3,4,5,6,7-pentaethylcyclodecene,1,5-cyclooctadiene, 1,5,9-cyclododecatriene,1,4,7,10-cyclododecatetraene, 2-methyl-6-ethylcyclooctadiene-1,4, andthe like, and mixtures thereof.

The catalysts which are useful for the present invention are those whichhave activity for the disproportionation of propylene into ethylene andbutenes. Some examples of such catalysts are

1. silica or thoria promoted by an oxide or a compound convertible tothe oxide by calcination or sulfide of tungsten or molybdenum or by anoxide or a compound convertible to the oxide by calcination of rheniumor tellurium;

2. alumina promoted with an oxide or compound convertible to an oxide bycalcination of molybdenum, tungsten, or rhenium; a sulfide of tungstenor molybdenum; or an alkali metal salt, ammonium salt, alkaline earthmetal salt, or bismuth salt of phosphomolybdic acid;

3. one or more of the group aluminum phosphate, zirconium phosphate,calcium phosphate, magnesium phosphate, or titanium phosphate promotedby one or more of a sulfide of molybdenum or tungsten, or an oxide or acompound convertible to the oxide by calcination of molybdenum, tungstenor rhenium or magnesium tungstate or beryllium phosphotungstate; and

4. silica, alumina, aluminum phosphate, zirconium phosphate, calciumphosphate, magnesium phosphate, or titanium phosphate promoted by ahexacarbonyl of molybdenum or tungsten.

The catalysts of (1) can be prepared and activated by conventionaltechniques such as by combining a catalyst grade silica with suitabletungsten, molybdenum, rhenium or tellurium compounds by a conventionalmethod such as, for example, impregnation, dry mixing, orcoprecipitation. Suitable tungsten and molybdenum compounds includetungsten oxide and molybdenum oxide and compounds convertible to theseoxides. The supported oxides are activated by calcining in air and thesupported sulfides are activated by heating in an inert atmosphere.

The catalysts of (2) can be prepared and activated by conventionaltechniques such as by combining catalyst grade alumina with an oxide ora compound convertible to an oxide by calcination of molybdenum,tungsten or rhenium and calcining the resulting mixture after removal ofany solvent used in the impregnation. The sulfides of tungsten ormolybdenum or the salts of phosphomolybdic acid can be utilized toimpregnate a catalyst grade alumina by solution in a proper solventafter which the solvent is evaporated and the resulting mixture dried toprepare the catalyst.

The catalyst compositions of (3) can be prepared and activated byconventional techniques. For example, molybdenum oxide can becoprecipitated with aluminum phosphate followed by calcination in air toproduce an activated catalyst. Alternatively, the support material canbe impregnated with a compound of the promoter convertible to the oxide,such as ammonium tungstate, followed by calcination in air. In thepreparation of a sulfide-containing catalyst, a sulfide of the promotercan be ball-milled with a support, such as zirconium phosphate, followedby heating in an inert atmosphere such as nitrogen. Magnesium tungstateand beryllium phosphotungstate can be dry mixed with titanium phosphate,for example, and activated by calcination in the air at elevatedtemperatures.

The catalyst compositions of (4) can be prepared and activated byimpregnating a previously calcined support material such as calciumphosphate with a solution of the hexacarbonyl of the promoter in anorganic solvent such as benzene, followed by drying in a vacuum or in aninert atmosphere at about 50° to 700° F.

The catalytic agent is considered to be the reaction product resultingfrom the admixture of the support material and the promoter materialwhich is subjected to activation treatment.

The operating temperature for the process of this invention when usingcatalysts of (1) is in the range of about 400° to 1100° F. The processof this invention when using the catalysts of (2) will be operated at atemperature in the range of about 150° to 500° F. The process using thecatalysts of (3) will be carried out at a temperature of about 600° to1200° F. The process using the catalysts of (4) will be carried out at atemperature of about 0° to 600° F. In the process of the invention,pressures are not important but will be in the range of about 0 to 2,000psig.

Other catalysts include those disclosed in Ser. No. 516,673, filed Dec.27, 1965; U.S. Pat. Nos. 3,261,879, issued July 19, 1966; 3,395,196,issued July 30, 1968; 3,442,969, issued May 6, 1969; 3,444,262, issuedMay 13, 1969; and 3,418,390, issued Dec. 24, 1968.

The finished catalyst can be in the form of powder, or granules as wellas in other shapes such as agglomerates, pellets, spheres, extrudates,beads, and depending upon the type of contacting technique whichutilizes the catalyst.

A wide variety of isomerization catalysts can be used. Preferredcatalysts are those which have little or no polymerization or crackingactivity and which are active for isomerization at conditions suitablefor obtaining a disproportionated product with the selecteddisproportionation catalyst. Some examples of suitable isomerizationcatalysts include supported phosphoric acid, bauxite, alumina supportedcobalt oxide or iron oxide or manganese oxide, zinc oxide, supportedalkali metal, and the like. Suitable catalysts can be selected fromamong those available in the art, such as the double bond isomerizationcatalysts listed in H. N. Dunning "Review of Olefin Isomerization", Ind.& Eng. Chem., 45, 551 (March 1953). Excellent results are obtained withmagnesium oxide.

When using magnesium oxide, the reaction can be accomplished attemperatures ranging from about 50° to about 1100° F., preferably about300° to about 900° F. at any suitable pressure and at residence times orthroughput rates which will effect the desired degree of isomerization.

Magnesia suitable for use in the invention can be any suitably activatedmaterial known in the art. The material normally has a surface area ofat least 1 m² /g. The magnesia can be naturally occurring, such as themineral Brucite, or can be synthetically prepared by suitabletechniques. Minor amounts of other materials such as silica, alumina,and the like, can be present, but the material is principally magnesiumoxide. Depending upon the contacting technique used for theisomerization, the activated magnesia can be in the form of pellets,extrudates, agglomerates, or even a fine powder. Before use in theprocess, the magnesium oxide is activated in a suitable manner such asby heating in a flowing stream of an oxygen-containing gas for about 1to about 30 hours at 500° to about 1500° F., preferably 600° to about1000° F. After activation sometimes it is advisable to flush thecatalyst with an inert gas to remove any adsorbed oxygen or other gasesfrom the magnesium oxide. The regeneration of spent magnesium oxideisomerization catalyst is generally accomplished by a technique which issimilar to the activation of this material.

When preparing a mixed bed of magnesium oxide and the olefin reactioncatalyst, particles of magnesium oxide and particles of the olefinreaction catalyst of about the same particle size can be blended.Alternatively, both magnesium oxide and the disproportionation catalystcan be intimately blended such as by grinding and the powder then formedinto other shapes such as pellets, tablets, agglomerates, extrudates,and the like, such that each particle in the catalytic zone comprises anintimate blend of the two catalysts.

Other appropriate techniques for obtaining a composite catalyst can beused.

The proportion of magnesium oxide to the disproportionation catalyst inthe composite catalyst system can vary widely. At least about 0.1 partby weight of magnesium oxide should be present for each part by weightof disproportionation catalyst and there is no theoretical upper limitfor the amount of magnesium oxide which can be present. Preferredratios, however, are 0.5 to about 20 parts by weight of magnesium oxideper part by weight of disproportionation catalyst. Equal parts of eachcatalyst give excellent results.

The conversion can be carried out at any convenient pressure up to about2000 psig or higher, preferably 0 to 500 psig, and at weight hourlyspace velocities (WHSV) of about 0.1 to about 1000 w/w/hr. The mixed bedprocess can utilize any suitable contacting technique such as fixed bedreactors, fluidized bed reactors, suspended catalyst systems, and thelike, and is effective with both gas phase and liquid phase operation.For example, for the conversion of normally liquid olefins, it issometimes convenient to utilize a refluxing technique wherein the olefincharge is heated to boiling in a vessel on top of which is mounted acolumn containing the desired catalyst combination. The olefin vaporscontact the catalyst and are converted to heavier olefins which arereturned to accumulate in the vessel and to lighter olefins which riseto the top of the column. A condenser is used to return any unconvertedolefin to the catalyst zone as a reflux while allowing the lighterproduct olefins to escape.

When using a metallic alkali metal treated olefin disproportionationcatalyst, a first step in the catalyst preparation comprises associatingmolybdenum oxide or tungsten oxide or a molybdenum or tungsten compoundconvertible to the oxide upon calcination with a support such asalumina, silica, or silica-alumina. This first step can be carried outby any suitable means for the preparation of catalysts such as byimpregnation, to obtain a composition containing from about 0.1 to about30, preferably 3 to 15, weight percent of molybdenum oxide or tungstenoxide based upon the total catalytic composition. Minor amounts of othermaterials which are compatible with the olefin reaction can also bepresent in the catalyst. Some of these are titania, magnesia, cobaltoxide, and small amounts of inorganic bases such as NaOH, KOH, and thelike. Some compositions particularly applicable for use in thisinvention comprise alumina impregnated with a molybdenum compound andwith a small amount of KOH. Such a component is then activated byheating in a stream of air or other oxygen-containing gas for 0.1 to 30hours at 700° to 1500° F., preferably 900° to 1100° F. After such anactivation, the oxide composite is flushed with an inert gas such asnitrogen and maintained at such an atmosphere throughout the rest of thepreparation until the finished catalyst is utilized in the reaction.

The activated oxide composite is contacted with metallic alkali metal inan amount which ranges from about 0.1 to about 30, preferably 2 to about10, weight percent based on the total weight of the finished catalyst.In the case of catalysts having a base predominantly silica, the amountof alkali metal preferably is about 0.1 to about 5 weight percent. Thecontact can be carried out by any suitable means such as by contactingthe solid oxide composite with either molten or vaporized alkali metal,such as sodium, for a period of time which may vary from about 1 minuteto about 10 hours. This can be accomplished using sodium, for example,by melting sodium and dropping the molten sodium on a molybdena-aluminacatalyst or by passing a stream of inert gas such as nitrogen or argonthrough the molten sodium and then over a bed of the molybdenaalumina.Contact of an alkali metal with the oxide composite generally isexothermic and causes the catalyst to take on a gray to black color.

The alkali metals utilizable in the process are selected from the groupconsisting of lithium, sodium, potassium, rubidium, cesium and mixturesthereof. Sodium and potassium are preferred in many instances withsodium being especially desirable.

In some instances, it has been found that pretreatment of the olefinfeed with activated magnesia at relatively low temperature isunexpectedly effective in improving the ease and efficiency of thesubsequent olefin reaction.

The purity of a feed is an important factor in any chemical process inthat it effects directly the efficiency of even operabiity of thatprocess. Olefin disproportionation processes in general require thesubstantial absence of materials which cause difficulty as, for example,by poisoning of the catalyst. Some of these impurities, for example,oxygen and water, are known; others are unknown. Activated magnesia isgreatly superior to many other absorption agents in the purification offeed streams for the olefin reaction. Any suitably activated magnesiacan be used for the pretreatment. For example, the magnesia as describedabove for use in the combination catalysts can be used. The benefits ofthe pretreatment can be obtained by contacting the feed with magnesiumoxide at relatively low temperatures which may be as low as the freezingpoint of the olefin being treated and may be as high as a point wheresignificant isomerization activity is observed. Frequently, ambienttemperatures such as room temperatures are satisfactory for an adequatepretreatment.

Any conventional contacting device can be used for the pretreatment. Forexample, the olefin can be treated by passing through a fixed orfluidized bed of activated magnesia or contact can be made by suspendingthe magnesia, by suitable agitation in the vessel containing the olefinto be treated. The contact with the magnesia can be either in vapor orliquid phase depending upon the nature of the olefin to be treated. Thetime of contact, throughput rate in regard to a fixed bed of magnesia,or magnesia usage per unit weight olefin, varies greatly with the olefinbeing treated and the degree of treatment which may be required to bringthe olefin into condition for reaction. Because the nature of theimpurities removed are not always known, the optimum extent of treatmentoften can best be determined by trial and error.

Such an olefin pretreatment with magnesia at relatively low temperaturesis advantageous even though magnesia may be present at a pointdownstream of the process, for example, where its isomerization activityis being exploited at somewhat higher temperatures.

Often in its use as an olefin treating agent, magnesium oxide slowlybecomes discolored and deactivated. It can be regenerated usingtechniques similar to those of its original activation.

Where desirable, magnesium oxide can be used in conjunction with otherknown adsorptive materials in the pretreatment step. For example,magnesium oxide can be used either consecutively or in mixture withalumina, silica gel, molecular sieve type materials, adsorptive clays,and the like. When used in mixture, the regeneration procedure should beselected to be compatible with all components of the treating mixture.In some instances, different regeneration techniques can be used, forexample, treatment with polar solvents or by first segregatingmechanically and isolating any temperature sensitive component forseparate treatment.

As indicated above, the specific reasons why olefin pretreatment withmagnesia is extremely beneficial in some instances is not known withcertainty. However, it is believed that the olefin reaction process maybe sensitive to such contaminants as peroxides and hydroperoxidecompounds in very low concentration and that magnesia is particularlyeffective in the removal of these and other impurities from olefins.

In one important embodiment of our invention, cyclic monoolefins areconverted to other cyclic monoolefins having a smaller ring size bycontact with the catalyst system in the presence of substantialquantities of ethylene. For example, cyclohexenes can be converted tocyclopentenes in substantial yields by contact with a catalyst systemcomprising magnesium oxide and silica supported tungsten oxide. Thecyclic monoolefins suitable for conversion in this manner are thosewhich contain from 6 to about 30 carbon atoms. The cyclic compounds canbe substituted with one or more alkyl groups having about 5 carbonatoms. However, when such substituents are present, the double bond mustbe isomerizable, that is, it must be able to be shifted at least oneposition. Excellent results are obtained with cyclic olefins containingup to about 20 carbon atoms per molecule and especially withunsubstituted monoolefins having from about 6 to about 12 carbon atoms.The proportion of ethylene to cyclic monoolefins introduced into thereaction zone generally is in the range of about 2 to about 30 moles ofethylene per mole of cyclic olefin but even greater quantities ofethylene can be utilized, limited only by the ability to separate andrecycle the unconverted ethylene conveniently. Generally, ethylene willbe present in the reactor effluent. The products which are obtained bythis process are cyclic monoolefins having at least one less carbon atomin the ring than in the original starting material. Propylene generallyis the major by-product. To insure high yields of such cyclic products,as opposed to larger amounts of lower molecular weight acyclic products,the operating conditions will include a combination of the shortestreaction times, the lowest temperatures, and the highest pressurescompatible with the specific catalyst utilized and conversion of thespecific cyclic olefins being converted. The effluent of the reactioncan be treated conventionally and desired products can be separated byany convenient means, such as by fractional distillation. Unconvertedethylene, as well as other olefinic products, not in the desiredmolecular weight range, can be recycled where appropriate.

In another important embodiment of this invention, acyclic polyenes orcyclic mono- or polyenes, having up to 30 carbon atoms per molecule, canbe converted to conjugated dienes by contact with a catalyst system ofthe invention in the presence of substantial quantities of ethylene.When the applicable olefinic materials are converted according to thisprocess, the products obtained, depending upon the feed materials, are1,3-butadiene, 2-methyl-1,3-butadiene, (isoprene),2,3-dimethyl-1,3-butadiene, isobutene and propylene. These products arethe fundamental products of this reaction which are not converted tolower molecular weight products. Thus, with suitable recycle andseparation techniques, the applicable olefinic materials can beexhaustively reduced to one or more of the fundamental products.Unbranched starting olefinic materials can produce 1,3-butadiene whilebranched olefinic starting materials can produce methyl substitutedbutadiene. Olefinic materials applicable for use in the presentinvention are olefins having from 5 to about 30 carbon atoms permolecule including isomerizable acyclic polyenes and isomerizable cyclicmono- or polyenes. The olefinic materials can be branched or unbranchedbut the presence of one or more quaternary carbon atoms will, barringskeletal isomerization, reduce the yields of conjugated dienes. Thepolyolefinic materials can contain from about 2 to about 5 double bondsper molecule and can be either conjugated or nonconjugated. Theproportion of ethylene to olefinic feedstocks introduced into thereaction zone will generally range from about 2 to about 30 moles ofethylene per mole of olefinic feedstock but even greater quantities ofethylene can be utilized, limited only by the ability to convenientlyseparate and recycle the unconverted ethylene. Generally ethylene shouldbe present in the reactor effluent. When the cyclic olefinic materialsare used as feedstocks, preferably the conversion is carried out atrelatively high temperatures, at relatively low reaction pressures, andat relatively low space velocities. Thus, increased conversion of suchcyclic olefinic materials to conjugated dienes is obtained at reactiontemperatures which are preferably above 700° F., at reaction pressureswhich are generally lower than about 500 psig, and at weight hourlyspace velocities which are generally lower than about 25 w/w/hr., or atother combinations of these conditions which give equivalent results.

In another important embodiment of this invention, acyclic monoolefinshaving up to about 30 carbon atoms are converted to propylene andisobutene by contact with a catalyst system of this invention in thepresence of substantial quantities of ethylene. The proportion ofethylene to cyclic monoolefins introduced into the reaction zonegenerally is in the range of about 2 to about 30 moles of ethylene permole of cyclic olefin but even greater quantities of ethylene can beutilized, limited only by the ability to separate and recycle theunconverted ethylene conveniently. When the conversion is carried outaccording to this process, it is possible to reduce any olefin ormixture of olefins to the fundamental products of the reaction, that is,to the products which can be reduced in molecular weight no further.These fundamental products are generally propylene or isobutene but canbe in some instances neohexene or substituted neohexene where thesubstituent is not on the vinyl group. This process finds particularutility in the removal of olefins from refinery streams from whicholefins are not ordinarily separable. The conversion ofolefin-containing refinery streams results in the degradation of thehigher molecular weight olefins to products such as propylene andisobutene which are readily separable by distillation. Gasoline streamsfrom which the olefins have been removed in this manner have increasedvalue in that they are less objectionable from the standpoint of motorvehicle hydrocarbon emissions. As a further advantage, propylene andisobutene which are removed from the gasoline stream can be converted tohigh octane values alkylates which can be returned to the gasoline tosignificantly increase the octane value of the gasoline. Acyclicmonoolefins which can be converted according to this process are thoseisomerizable olefins having from about 4 to about 30 carbon atoms permolecule. They can be branched or unbranched but the presence of one ormore quaternary carbon atoms in the molecule will, barring skeletalisomerization, reduce the reactivity of the olefin. The compound2,4,4-trimethylpentene-2 is readily convertible to isobutene but this isgenerally the result of strong inclination to crack at elevatedtemperatures. The proportion of ethylene to the acyclic monoolefinsgenerally is at least 2:1 but there is no theoretical upper limit.However, practical limits, determined by considerations of separationand recycle generally will be about 20:1. When it is desired tocompletely convert large molecules, greater quantities of ethylene arerequired such that an excess of ethylene is always present in theeffluent.

The invention is further illustrated by the following examples:

EXAMPLE I

Pentene-2 was disproportionated in two runs. The conversion was carriedout continuously by passing the pentene-2 through a stainless steelreactor tube which contained the catalyst maintained at 700° F. In onerun, the catalyst bed consisted of 3.2 parts by weight of 30-50 meshparticles of a tungsten oxide on silica catalyst which had beenair-activated and then given a post-activation treatment with CO at1000° F. for 45 minutes at atmospheric pressure. In the second run, thecatalyst charge consisted of a blend of 2.7 parts by weight of theabove-described tungsten oxide on silica catalyst and 2.75 parts byweight of 30-50 mesh particles of magnesium oxide. The essential dataand the results of these runs, in terms of the effluent analysis, areshown in the following table.

                                      TABLE I                                     __________________________________________________________________________    FIXED BED DISPROPORTIONATION OF PENTENE-2 AT 700° F.                   __________________________________________________________________________                   With MgO    Without MgO                                        __________________________________________________________________________    Pressure, psig 100   200   100   200                                          Rate, g feed/g WO.sub.3 cat/hr                                                               49    51    50    52                                           Effluent analysis, wt. %                                                      C.sub.2 =      0.06  0.60  0.00  0.00                                         C.sub.3 =      2.37  2.47  1.00  0.68                                         C.sub.4 =      11.18 12.17 7.64  9.10                                         C.sub.5 =      71.60 66.10 82.10 78.60                                        C.sub.6 =      10.51 11.90 7.97  9.64                                         C.sub.7 =      3.86  4.82  1.16  1.93                                         C.sub.8 =      0.36  0.92  0.00  0.00                                         Conversion, %  28.4  33.90 17.90 21.40                                        __________________________________________________________________________

The data clearly show that under comparable conditions, the catalystsystem containing the magnesium oxide resulted in a greater conversionof pentenes and a broader distribution of olefin products.

EXAMPLE II

Pentene-1 containing an unknown contaminant or contaminant detrimentalto disproportionation was disproportionated in a run demonstrating theeffectiveness of magnesium oxide pretreatment at relatively lowtemperatures and improving the conversion level. The run was carried outusing a commercial pentene-1 having a purity greater than 99.0 percentin a continuous reactor at 100 psig and 537 WHSV by passing the feedsequentially through a bed consisting of 10 parts by weight of granularmagnesium oxide and a bed consisting of a mixture of 14 parts by weightof granular magnesium oxide and 2 parts by weight of granular tungstenoxide supported on silica. These adjacent beds were maintained at 775°F. during the run. During the initial part of the run, the feed waspretreated by passing through a bed consisting of 50 parts by weight ofgranular magnesium oxide preceded by 10 parts by weight of granularsilica gel at ambient temperatures. During the latter part of the run,the pretreatment was omitted. The results are set forth in Table IIbelow.

                  TABLE II                                                        ______________________________________                                        Time on stream (minutes)                                                                        Conversion (percent)                                        ______________________________________                                         5                73.5                                                        12                71.9                                                        19                72.5                                                        26                72.5                                                        33                71.2                                                        At this point, the pretreatment was discontinued.                             38                75.4                                                        44                67.8                                                        53                16.1                                                        63                 0.5                                                        75                 0.4                                                        ______________________________________                                    

EXAMPLE III

In this run, cyclohexene and ethylene were continuously converted in afixed bed reactor. The tubular steel reactor contained, as the catalyticbed, a mixture of 5 parts by weight of a silica-supported tungsten oxidecatalyst (-20 + 65 mesh) and 12 parts by weight of a magnesium oxidecatalyst (-20 + 50 mesh). This intimately mixed catalyst was chargedinto the center of the reactor with steel packing both above and belowit. The catalyst bed was activated by heating to 1000° F. in thepresence of flowing air for three hours. After the air treatment, carbonmonoxide was then passed over the catalyst for 10-15 minutes and thereactor was cooled to 700° F. under a carbon monoxide atmosphere.

A mixture of ethylene and cyclohexene was then passed through thereactor at 700° F., 400 psig, and at a weight hourly space velocity of13.5 w/w/hr., based upon the cyclohexene. The molar ratio of ethylene tocyclohexene was 7.6.

After being on stream for one hour, the effluent reactor was analyzed.The analysis showed that the conversion of reactants was about 29.8percent with about 45.6 weight percent of the products being propylene,19.9 weight percent being cyclopentene, 10.6 weight percent beingbutadiene, and small amounts of other hydrocarbons, principally mono-and diolefins, making up the remainder.

EXAMPLE IV

The run of Example III was repeated under essentially the sameconditions except that the reaction pressure was 750 psig.

The feed stream for the reactor consisted of an 8.7 mole ratio ofethylene to cyclohexene (which had previously been percolated through abed of silica gel and magnesia at room temperature). The conversion wascarried out at 700° F., 750 psig, and at weight hourly space velocity of11.8 w/w/hr.

After being on stream for about 1 hour, the effluent from the reactorwas analyzed. The analysis indicated a 35.3 percent conversion ofcyclohexene with 55.0 weight percent of the products being propylene,18.8 weight percent being cyclopentene, 12.4 weight percent beingbutadiene, about 2.6 weight percent believed to be 1,7-octadiene, andsmall amounts of other hydrocarbon products making up the remainder.

These runs illustrate that the process of the present invention iscapable of converting cyclohexene to substantial amounts of cyclopenteneand propylene.

EXAMPLE V

Ethylene and cyclopentene were continuously converted in a fixed bedreaction. The tubular steel reactor contained, as the catalytic bed, amixture of 5 parts by weight of a silica/tungsten oxide catalyst (-20 +65 mesh) and 12 parts by weight of a magnesia catalyst (-20 + 35 mesh).This intimately mixed catalyst was charged into the center of thereactor with steel packing both above and below it. The catalyst bed wasactivated by heating the reactor and catalyst bed to 1000° F. in thepresence of flowing air for 3 hours. After the air treatment, carbonmonoxide was passed over the catalyst for ten minutes and the reactorwas cooled to 700° F. under a carbon monoxide atmosphere.

The feed stream consisted of ethylene and cyclopentene (which hadpreviously been percolated at room temperature through a silica gel andmagnesia bed) having a mole ratio of 7.3. The conversion was carried outat 700° F., 400 psig, and at a weight hourly space velocity of 11.7w/w/hr (based on the cyclopentene).

After being onstream for about one hour, the effluent from the reactorwas analyzed. The analysis showed that about 30 percent of the reactantswere converted, with about 50 weight percent of the products beingpropylene, about 25 weight percent of the products being butadiene,about 8.6 weight percent believed to be 1,6-heptadiene, and severalother products believed to be butene-2, butene-1, and isobutylene.

These data show that cyclopentene can be effectively converted tobutadiene and propylene in high ultimate yields by using the process ofthe present invention.

EXAMPLE VI

A tubular steel reactor was charged with a mixture of 3 parts by weightof silica/tungsten oxide catalyst (-20 + 50 mesh) and 12 parts by weightmagnesia (-20 + 50 mesh) to form a catalytic bed. Steel packing was alsocharged into the reactor both below and above the bed. The catalyst bedwas then activated by heating the reactor and bed at 1000° F. in flowingair for three hours followed by contact with flowing carbon monoxide for10 minutes. The reactor was then cooled to 700° F. under a carbonmonoxide atmosphere.

The feedstock for this run was a cat-cracked gasoline (800 parts byvolume) which had been fractionated to remove the light ends boilingbelow 75° C. (200 parts by volume) and to leave behind the heavy endsboiling above 265° C. (75 ml). This gasoline fraction was percolatedthrough a bed of silica gel and magnesia at room temperature and thenpassed through the reactor together with sufficient ethylene to providea 11.1 mole ratio of ethylene to the gasoline (having an estimatedaverage molecular weight of about 126). The conversion was carried outat 400 psig, 700° F., and at a weight hourly space velocity of 16.2w/w/hr. based on the gasoline.

After being on stream for about 45 minutes, the effluent from thereactor was analyzed. The analysis indicated that about 20 percent ofthe gasoline fraction was converted. The major olefinic productsobtained were propylene in an amount of 45.5 weight percent, andisobutene in an amount of 38.6 weight percent. Other C₄ and C₅ olefinicproducts were also observed. The analysis indicated that essentially allof the olefins originally present in the gasoline fraction wereconverted. Comparable runs carried out thermally or with only themagnesium oxide present gave only traces of the products obtained in theabove run. This illustrates that a combination of the magnesium oxideand the silica/tungsten oxide improves the results obtained.

The data above show that the present invention can very effectivelyremove olefins from complex refinery streams by converting olefinicmaterials to other olefins such as propylene or isobutene which areeasily separable from the refinery stream.

EXAMPLE VII

397 parts by weight of a commercial molybdena-alumina (in the form of1/8 inch pellets containing about 12.45 weight percent molybdena) werecontacted with about 42 parts by weight of a KOH solution (containing0.0577 g KOH/ml) diluted with about 540 parts by weight of distilledwater. The mixture was agitated and allowed to stand. The aqueous phasewas tested and found to be neutral to litmus paper after 25 minutes.After 2.25 hours the aqueous phase was decanted and the pellets dried byheating by a water bath under vacuum.

The above material was activated at 990° F. under a stream of air for 3hours. The catalyst was flushed and stored under nitrogen until furtheruse. 28.5 parts by weight of the above oxide composite was flushed withnitrogen and kept under a nitrogen atmosphere. 2 parts by weight ofsodium metal was placed in the same vessel with the oxide composite andheated. At about 208° F. the sodium melted and combined with the pelletsturning them black. The supply of heat was removed and the temperatureincreased exothermically to about 280° to 300° F. No free sodium metalwas visible.

15.2 parts by weight of the above prepared sodium-treatedmolybdenaalumina catalyst was charged to a nitrogen flushed tube. 21.6parts by weight of octene-4 was placed in a vessel and the tube mountedon the top thereof. The vessel was heated and the octene-4 was refluxedover the catalyst at ambient pressure. The refluxing and reaction wereallowed to proceed for 82 minutes during which the temperature in thevessel increased to 347° F. The contents of the vessel were then sampledand analyzed by gas-liquid chromatography. The results of the analysisare shown in Table III.

For purposes of comparison, a similar conversion of octene-4 was carriedout with the exception that the catalyst consisted on a molybdenaaluminawhich had been treated with 0.5 weight percent KOH but had not beentreated with metallic sodium. After 177 minutes, the temperature in thevessel had reached only 275° F. The contents of the reactor were sampledand similarly analyzed and also appear in Table III.

                                      TABLE III                                   __________________________________________________________________________    Catalyst                                                                      Pot Temp., ° C.,                                                                 Al.sub.2 O.sub.3 --MoO.sub.3 (0.5 wt. % KOH)                                                 Na (6.5 wt. %)--Al.sub.2 O.sub.3 --MoO.sub.3         reached in min.                                                                         130.5° C./177 min.                                                                    (0.7 wt. % KOH) 175° C./82                    __________________________________________________________________________                             min.                                                           Wt. %  Mol. %  Wt. %   Mol. %                                       __________________________________________________________________________    C.sub.3 = --             0.07    0.22                                         C.sub.4 = 0.19   0.40    1.01    2.36                                         C.sub.5 = 0.69   1.15    3.22    6.00                                         C.sub.6 = 2.28   3.16    5.97    9.28                                         C.sub.7   9.40   11.15   5.04    6.71                                         C.sub.8 = 43.40  45.10   7.58    8.82                                         C.sub.9   28.60  26.40   11.70   12.11                                        C.sub.10 =                                                                              12.08  10.03   20.35   18.98                                        C.sub.11 =                                                                              2.90   2.19    20.15   17.09                                        C.sub.12 =                                                                              0.45   0.31    14.71   11.43                                        C.sub.13 =                                                                              --     --      6.49    4.65                                         C.sub.14 =                                                                              --     --      2.59    1.72                                         C.sub.15 =                                                                              --     --      1.16    0.71                                         __________________________________________________________________________

The data in Table III clearly show that the conversion of octene-4 overthe sodium-treated catalyst resulted in a much greater conversion in ashorter length of time. The greater conversion is indicated by thesmaller quantity of octenes present in the reaction vessel at thecompletion of the test, the greater number of olefin reaction products,and greater quantities of olefin reaction products.

Reasonable variation and modification are possible within the scope ofthe invention which sets forth a method for the olefin reaction.

What is claimed is:
 1. A composition active for converting an olefin toobtain the product of the olefin reaction which, as defined herein, canbe visualized as comprising the reaction between two first pairs ofcarbon atoms, the two carbon atoms of each first pair being connected byan olefinic double bond, to form two new pairs from the carbon atoms ofsaid first pairs, the two carbon atoms of each of said new pairs beingconnected by an olefinic double bond comprising magnesium oxide admixedwith a separate disproportionation catalyst selected from the groupconsisting ofalumina promoted by an oxide or compound convertible to anoxide by calcination of molybdenum, tungsten or rhenium; a sulfide oftungsten or molybdenum; or an alkali metal salt, ammonium salt, alkalineearth metal salt, or bismuth salt of phosphomolybdic acid; saidmagnesium oxide being present in an amount in the range of 0.1 to 20parts by weight per part by weight of said disproportionation catalyst.2. The composition of claim 1 wherein said disproportionation catalystcomprises molybdenum oxide on alumina.
 3. The composition of claim 1wherein said magnesium oxide is present in an amount in the range of 0.5to 20 parts by weight per part by weight of said disproportionationcatalyst.
 4. The composition of claim 3 wherein said disproportionationcatalyst comprises molybdenum oxide on alumina.